INDEX 



Mercury arc: 



anode drop in, 97. 



electric force in, 97. 



in quartz tubes, 100. 



velocity of ions in, 101. 



modification of, to produce white 

 light, 102. 



rectifier, 120. 



with alternating currents, 124. 



photometry of, 134. 



candle power of, 134, 139, 142. 

 Merritt atid Stewart, 177. 

 Metal electrodes: 



arc with, 61. 



characteristic curves with, 62. 



hissing arcs with, 65. 



anode and cathode drops with, 65. 



different metals used for, 66, 81, 



"5- 



in a vacuum, 81. 



with alternating currents, 114. 



photometry of, 134. 

 Metteucci, 62. 

 Microphone and wireless telephony, 



154. 



Milkiewicz, 38. 

 Moissan, 40. 

 Monash, Guye and, 115. 

 Morris, 51, 120. 

 Mutter, de la Rue and, 74. 



N 



Negative electrode, see Cathode. 

 Negative ions, 157. 

 Negative resistance, 31. 

 Nitrogen arc in, 84. 

 Non-arcing metals, 114. 

 Norden, 124. 



O 



Olivette, 38. 

 Oscillograph, 38. 



Oscillographs of: 



hissing arc, 21. 



arc in magnetic field, 51. 



alternating-current arc, 109. 

 Oxides, arc between, 67. 

 Oxygen, arc in, 85. 



Petavel, 41, 132. 

 Petavel, Fleming and, 127, 137. 

 Phase difference between current 

 and voltage with alternating- 

 current arcs, 113. 

 Photometry: 



difficulties in, 126. 



of direct-current carbon arc, 128. 



of flaming arc, 132. 



of metal arcs, 134. 



of mercury arc, 134. 



of alternating-current arc, 135. 



See also Candle power. 

 Planck's law, 43. 

 Pollak, 96, 98, 175. 

 Pollock, 34. 



Pollock and Ranchaud, 52. 

 Positive electrode, see Anode. 

 Positive ions, 157. 

 Potassium alloy, 82. 

 Potential difference between ter- 

 minals of: 



carbon arc, 9. 



arc in vacuum, 78, 79. 



arc in hydrogen, 86. 



See also Characteristic curves. 

 Potential difference with different 

 phases of alternating-current 

 arc, 107. 



Potential gradient, see Electric force. 

 Potential within arc, 22, 160. 

 Poulsen, 151. 

 Power used in arc, 14. 



